Grounding And Termination - ABB ACS 400 User Manual

Grounding and Termination

RS485 Bus
The RS485 network should not be directly grounded at any point. All the devices on the network
should be well grounded using their corresponding earthing terminals.
As always, the grounding wires should not form any closed loops, and all the devices should be
earthed to a common ground.
The RS485 network must be terminated using 120 Ω resistors at both ends of the network. Use DIP
switch to connect or disconnect the termination resistors.
The termination should not be done on the intermediate stations on the network as shown in Figure
57.
Terminated Terminated
Figure 57 Termination for the RS485 link.
The connections may only be made with the drive disconnected from the power source.
ACS 400 User's Manual 131
http://nicontrols.com